Working With Nulls in SQL Server

Nulls are basic to SQL Server, but basic isn't the same as obvious. Make the mistake of typing "middlename = null" instead of "middlename is null" and no error message is thrown, the query runs, but you get the wrong answer. Nulls are an important part of database design and like any tool can be used or abused, but once you have the potential for nulls in a column, then you have to know how they work and how to make sure you get back the right answers.

Andy Warren is a software trainer focusing on SQL Server, a member of the PASS Board of Directors, and a principal in this site - SQLShare.com.

simon on 9/27/2010

Great stuff !

punjwani on 9/27/2010

Excellent presentation.

Kristeen Sellers on 9/27/2010

Interesting. However, I tend to you isnull(variablename, '') = '' rather than variablename is null. I have found that in SQL 7, the is null did not always work correctly and I still code that way for SQL 2005 & SQL 2008.

Lawrence on 9/27/2010

COALESCE(value1, value2, value3, ...) would be a nice addition to this topic.

Laura on 9/27/2010

Clear and to the point. Great Job!

Leonard Peoples on 9/27/2010

A good base will save us time. If someone's been coding in SQL for years, they may stumble on this and waist time every time this comes up. I know I've tried = NULL and <> NULL. But I won't anymore. Thanks...

Craig on 9/27/2010

Oy with the throat clearing. Edit that out please!

Alexander on 9/27/2010

very nice video

Phil on 9/27/2010

Very well organized and presented.

Keith Nessel on 9/27/2010

Great information - and reminder.

nilanaksha on 9/27/2010

Good One. Just to share, we can use = NULL in the queries if ANSI_NULLS is set to OFF.

anand on 9/28/2010

Good Video on Null basics.

Kasey Wheeler on 9/28/2010

Good Vid

Jeromy Kimani on 9/28/2010

As always great commentary from Andy.

ananth venkitaraman on 9/30/2010

Very good point is the different behaviour of versions like 6.5 and 2008 for people who worked with older versions.

Diana Dee on 9/30/2010

Nice and basic! I did not know that integer variables are set to 0 automatically when declared. Please watch when scrolled to the right and magnified. There was a section of video in which you had done that and the left side with code and results was cut off and not visible.

SQLSharma on 10/2/2010

Keep up the good stuff,despite non-Monday Mondays...Thanks Andy!

manik on 10/6/2010

will help handling nulls a lot.

Sandra Barnes on 10/8/2010

A lot of coughing, throat clearing for a 6 min video.

lital on 10/12/2010

Great site!!! thanks.

lital on 10/12/2010

Great site!!! thanks.

vijay on 11/10/2010

Good Demo

Bhushan on 7/10/2011

Good short video...did not know the difference between '= null', 'is null', '<> null' and 'is not null'. Still do not very much understand it; but can manage it now by executing it on a different set of data myself.